For rational expressions, all real numbers can be used as inputs, except for those that make the denominator equal to 0 (since division by 0 is undefined).
Thus, the domain restrictions are values that turn the denominator into 0. Since you have (x + 2) (x - 1) as the denominator, then it means that:
For (x + 2), the value of x CANNOT be -2, as it will result into 0.
For (x - 1), the value of x CANNOT be 1 because their difference will have 0 as a result.
Therefore, the correct answers are:
b.) x = 1
c.) x = -2
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